Ecophysiology of Fusarium chaquense a Novel Type A Trichothecene Producer Species Isolated from Natural Grasses

Fusarium chaquense, a recently formally described novel species, has been identified as an T-2 toxin (T-2), HT-2 toxin (HT-2) and other toxins producer in natural grasses (Poaceae) from Argentina. The major objective of this study was to describe the effect of water activity (aW, 0.995, 0.98, 0.95, 0.93 and 0.91), temperature (15, 25 and 30 °C) and incubation time (5, 15 and 25 days) on growth and to evaluate the production of T-2, HT-2 toxins and beauvericin (BEA) by two F. chaquense strains in a grass-based media. The results showed a wide range of conditions for F. chaquense growth and mycotoxin production. Both strains had a maximum growth rate at the highest aW (0.995) and 25 °C. Regarding mycotoxin production, more T-2 than the other analysed mycotoxins were produced by the two strains. T-2 production was favoured at 0.995 aW and 30 °C, while HT-2 production at 0.98–0.95 aW and 15 °C. The maximum levels of BEA were produced at 0.995 aW and 25–30 °C. Two-dimensional profiles of aW by temperature interactions were obtained from these data in order to identify areas where conditions indicate a significant risk of mycotoxins accumulation on grass. For its versatility on growth and mycotoxin production in a wide range of aW and temperatures, F. chaquense would have an adaptive advantage over other Fusarium species, and this would explain its high frequency of isolation in natural grasses grown up in the Chaco wetlands.

Consistent Trait-Temperature Interactions Drive Butterfly Phenology in Both Incidental and Survey Data

Data availability limits phenological research at broad temporal and spatial extents. Butterflies are among the few taxa with broad-scale occurrence data, from both incidental reports and formal surveys. Incidental reports have observation biases that are challenging to address, but structured surveys are often limited seasonally and may not span full flight phenologies. Thus, which data source is more useful for phenological analyses is unclear. We use parallel analyses of incidental and survey data to determine how traits and climate drive phenological patterns for common butterflies. One workflow aggregated “Pollard” surveys, where sites are visited multiple times per year; the other aggregated incidental data from online portals: iNaturalist and eButterfly. For 40 routinely observed resident species, we estimated early (10%) and mid (50%) flight period metrics, and compared the spatiotemporal patterns and drivers of phenology across species and between datasets. Results were similar between datasets. Inter-annual variability was best explained by temperature, and seasonal emergence was earlier for resident species that overwinter at more advanced stages. Other traits had mixed or no impacts. The consistency in results suggests that data integration can improve phenological research, and leveraging traits may predict phenology in poorly studied species.

Laser Heating Study of the High-Temperature Interactions in Nanograined Uranium Carbides

Nanograined nuclear materials are expected to have a better performance as spallation targets and nuclear fuels than conventional materials, but many basic properties of these materials are still unknown. The present work aims to contribute to their better understanding by studying the effect of grain size on the melting and solid–solid transitions of nanograined UC2−y. We laser-heated 4 nm–10 nm grain size samples with UC2−y as the main phase (but containing graphite and UO2 as impurities) under inert gas to temperatures above 3000 K, and their behavior was studied by thermal radiance spectroscopy. The UC2−y solidification point (2713(30) K) and α-UC2 to β-UC2 solid–solid transition temperature (2038(10) K) were observed to remain unchanged when compared to bulk crystalline materials with micrometer grain sizes. After melting, the composite grain size persisted at the nanoscale, from around 10 nm to 20 nm, pointing to an effective role of carbon in preventing the rapid diffusion of uranium and grain growth.

Nanometer-thin pure boron CVD layers as material barrier to Au or Cu metallization of Si

Metallization layers of aluminum, gold, or copper are shown to be protected from interactions with silicon substrates by thin boron layers grown by chemical-vapor deposition (CVD) at 450 °C. A 3-nm-thick B-layer was studied in detail. It formed the p+-anode region of PureB diodes that have a metallurgic junction depth of zero on n-type Si. The metals were deposited by electron-beam-assisted physical vapor deposition (EBPVD) at room temperature and annealed at temperatures up to 500 °C. In all cases, the B-layer was an effective material barrier between the metal and Si, as verified by practically unchanged PureB diode I–V characteristics and microscopy inspections of the deposited layers. For this result, it was required that the Si surface be clean before B-deposition. Any Si surface contamination was otherwise seen to impede a complete B-coverage giving, sometimes Schottky-like, current increases. For Au, room-temperature interactions with the Si through such pinholes in the B-layer were excessive after the 500 °C anneal.

Thermal niches of specialized gut symbionts: the case of social bees

Responses to climate change are particularly complicated in species that engage in symbioses, as the niche of one partner may be modified by that of the other. We explored thermal traits in gut symbionts of honeybees and bumblebees, which are vulnerable to rising temperatures. In vitro assays of symbiont strains isolated from 16 host species revealed variation in thermal niches. Strains from bumblebees tended to be less heat-tolerant than those from honeybees, possibly due to bumblebees maintaining cooler nests or inhabiting cooler climates. Overall, however, bee symbionts grew at temperatures up to 44°C and withstood temperatures up to 52°C, at or above the upper thermal limits of their hosts. While heat-tolerant, most strains of the symbiont Snodgrassella grew relatively slowly below 35°C, perhaps because of adaptation to the elevated body temperatures that bees maintain through thermoregulation. In a gnotobiotic bumblebee experiment, Snodgrassella was unable to consistently colonize bees reared at 29°C under conditions that limit thermoregulation. Thus, host thermoregulatory behaviour appears important in creating a warm microenvironment for symbiont establishment. Bee–microbiome–temperature interactions could affect host health and pollination services, and inform research on the thermal biology of other specialized gut symbionts.

PSVIII-6 Effect of Pellet Die Thickness and Conditioning Temperature During the Pelleting Process on Phytase Stability

This experiment evaluated the effects of pellet die thickness and conditioning temperature on microbial phytase stability. Treatments were arranged as a 2 × 3 factorial of die thickness (5.6 and 8.0 length:diameter [L:D]) and conditioning temperature (74, 79, and 85°C). Phytase was added to a corn-soybean meal-based diet. The diet was steam conditioned (245 × 1397 mm Wenger twin staff pre-conditioner, Model 150) and pelleted (CPM Model 1012-2) with a 4 × 22.2 mm (5.6 L:D) or 4 × 31.8 mm (8.0 L:D) pellet die. Conditioner retention time was set at 30 s and production rate was set at 15 kg/min. All treatments were replicated over 3 days. Conditioned mash and pellet samples were collected and immediately placed in an experimental counter-flow cooler for 15 min. Samples were analyzed for phytase activity and pellet durability index (PDI). Conditioning temperature, hot pellet temperature (HPT), and production rate were recorded throughout each processing run. Data were analyzed using PROC GLIMMIX in SAS (v. 9.4), with pelleting run as the experimental unit and day as the blocking factor. There was no evidence (P >0.14) for any die thickness × conditioning temperature interactions. Pelleting with the 8.0 L:D die increased (P < 0.01) HPT (83.2 and 84.2°C) and PDI (81.9 and 89.7%). Increasing conditioning temperature from 74 to 85°C increased (linear, P< 0.03) HPT (80.1, 83.6, and 87.5°C , respectively) and PDI (84.3, 84.9, and 88.2%, respectively) and decreased (linear, P< 0.01) phytase stability from 97.1 to 35.8% in conditioned mash and from 60.8 to 25.9% in cooled pellets. There was no difference (P >0.72) in stability due to die thickness. Results of this experiment demonstrated phytase stability decreased linearly as temperature rose above 74°C. Although the thicker pellet die increased HPT and PDI, the rise in HPT was not great enough to reduce phytase stability.

Germination of Cenchrus ciliaris, Pennisetum divisum, and Panicum turgidum is seasonally dependent

Knowledge of optimal conditions for germination facilitates more efficient practices, such as fodder production and restoration. We assessed seeds of three grass species harvested in winter and summer 2018. Germination ability was assessed under two night/day temperature regimes (15 °C/20 °C, 20 °C/30 °C) and two photoperiod regimes (0, 12 h light per day). Winter-maturing seeds had a slightly lower mass and reduced germination. Temperature and light requirements for optimal germination were dependent on species and harvest-time. Summer-maturing seeds of all three species had higher germination rates regardless of germination temperature. Interactions among treatment temperatures and species were 0.7- to 5.4-times higher than the control, as shown by heatmaps. Therefore, attention to these factors will improve the efficiency of seedling establishment for rehabilitation work.

Thermal niches of specialized gut symbionts: the case of social bees

Responses to climate change are particularly complicated in species that engage in symbioses, as the niche of one partner may be modified by that of the other. We explored thermal traits in gut symbionts of honeybees and bumblebees, which are vulnerable to rising temperatures. In vitro assays of symbiont strains isolated from 16 host species revealed variation in thermal niches. Strains from bumblebees tended to be less heat-tolerant than those from honeybees, possibly due to bumblebees maintaining cooler nests or inhabiting cooler climates. Overall however, bee symbionts grew at temperatures up to 44 °C and withstood temperatures up to 52 °C, at or above the upper thermal limits of their hosts. While heat-tolerant, most strains of the symbiont Snodgrassella grew relatively slowly below 35 °C, perhaps because of adaptation to the elevated body temperatures that bees maintain through thermoregulation. In a gnotobiotic bumblebee experiment, Snodgrassella was unable to consistently colonize bees reared below 35 °C under conditions that limit thermoregulation. Thus, host thermoregulatory behavior appears important in creating a warm microenvironment for symbiont establishment. Bee-microbiome-temperature interactions could affect host health and pollination services, and inform research on the thermal biology of other specialized gut symbionts, such as those of humans.